LQ9 Stroker block
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From: Mundelein,Illinois
LQ9 Stroker block How big a bore can this block be taken to? Can I run a 4.100 or 4.125 stroke? Is it better to gain cubic inches thru larger bore or longer stroke? Sorry with all the questions, I'm new to the LSx world. Thanks
TECH Fanatic
Joined: Jun 2011
Posts: 1,343
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From: Katy, TX
A 4" stroke and 0.030" bore are very common and result in a 408. A 0.060" bore is less common, but plenty of people run it. Some even run up to 0.100" bore with ultrasonic wall thickness checks.
Anything over a 4" stroke will require clearancing inside the block to clear the rod bolts.
Anything over a 4" stroke will require clearancing inside the block to clear the rod bolts.
There is a debate going on about using more than a 4" stroke crank with a 6.0 block. The argument is that a 4.1+" crank will pull the piston skirt out of the bore at the bottom of the stroke far enough to cause premature wear on the skirts and the bores. Some people claim to have done it sucessfully, some have claimed to have done it and experienced complications. There is no definitve proof yet to wein the debate either way, just "i dids, and he saids". The safest bet is to have the block sonic tested and go with the appropriate bore, or you can chance it and go with the longer stroke.
If this a street driven car and/or if you want longevity, I'd say stay with a 4.030" bore and a 4.000" stroke. The LQ9 "usually" be bored to LS3 size (4.065") if you sonic test the block first. Anything bigger starts to be hit and miss. If you really want to go large displacement, then get a LSX block. They can handle up to 4.185" bore and 4.125" stroke.
TECH Apprentice
Joined: Oct 2007
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There is a debate going on about using more than a 4" stroke crank with a 6.0 block. The argument is that a 4.1+" crank will pull the piston skirt out of the bore at the bottom of the stroke far enough to cause premature wear on the skirts and the bores. Some people claim to have done it sucessfully, some have claimed to have done it and experienced complications. There is no definitve proof yet to wein the debate either way, just "i dids, and he saids". The safest bet is to have the block sonic tested and go with the appropriate bore, or you can chance it and go with the longer stroke.
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The definative BEST way to increase cubic inches for racing is more bore and
less stroke (NASCAR and PRO STOCK). Larger bores unshroud big valves and
large runner heads while short strokes reduce piston speed & rod angularity.
Rod angularity is what rocks the piston in the bore..hammering the skirts and
causing ring flutter which reduces sealing of combustion...hence they end up
using oil !!!! A quick veiw of ERL's website explains how the sleeves that they
put in aluminum blocks are longer to support the piston @ BDC when it's be-
ing driven into the skirts with 4",4.1",& 4.125" long arms. Now don't get me
wrong, I'm not bashing strokers as I've run quite a few over the years but to
me they're better suited for low RPM type street motors(trucks, heavy cars,
etc.)...unless you have the caliber of pocket book to maintain and freshen
often...which I never did. Fact is that 60% of an engine's rotating friction is
from the piston speed and ring tension. Shorter strokes make for less cubic
inches but will always be more efficient (horspower per in^3)..IIWM I'd go
for the LSX block @ 4.185"-4.200"bore range and a killer aftermarket (Lunati
or Callies) 3.62 crank for a 39x inch rev-happy horsepower beast.
less stroke (NASCAR and PRO STOCK). Larger bores unshroud big valves and
large runner heads while short strokes reduce piston speed & rod angularity.
Rod angularity is what rocks the piston in the bore..hammering the skirts and
causing ring flutter which reduces sealing of combustion...hence they end up
using oil !!!! A quick veiw of ERL's website explains how the sleeves that they
put in aluminum blocks are longer to support the piston @ BDC when it's be-
ing driven into the skirts with 4",4.1",& 4.125" long arms. Now don't get me
wrong, I'm not bashing strokers as I've run quite a few over the years but to
me they're better suited for low RPM type street motors(trucks, heavy cars,
etc.)...unless you have the caliber of pocket book to maintain and freshen
often...which I never did. Fact is that 60% of an engine's rotating friction is
from the piston speed and ring tension. Shorter strokes make for less cubic
inches but will always be more efficient (horspower per in^3)..IIWM I'd go
for the LSX block @ 4.185"-4.200"bore range and a killer aftermarket (Lunati
or Callies) 3.62 crank for a 39x inch rev-happy horsepower beast.
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iTrader: (40)
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From: Mundelein,Illinois
The definative BEST way to increase cubic inches for racing is more bore and
less stroke (NASCAR and PRO STOCK). Larger bores unshroud big valves and
large runner heads while short strokes reduce piston speed & rod angularity.
Rod angularity is what rocks the piston in the bore..hammering the skirts and
causing ring flutter which reduces sealing of combustion...hence they end up
using oil !!!! A quick veiw of ERL's website explains how the sleeves that they
put in aluminum blocks are longer to support the piston @ BDC when it's be-
ing driven into the skirts with 4",4.1",& 4.125" long arms. Now don't get me
wrong, I'm not bashing strokers as I've run quite a few over the years but to
me they're better suited for low RPM type street motors(trucks, heavy cars,
etc.)...unless you have the caliber of pocket book to maintain and freshen
often...which I never did. Fact is that 60% of an engine's rotating friction is
from the piston speed and ring tension. Shorter strokes make for less cubic
inches but will always be more efficient (horspower per in^3)..IIWM I'd go
for the LSX block @ 4.185"-4.200"bore range and a killer aftermarket (Lunati
or Callies) 3.62 crank for a 39x inch rev-happy horsepower beast.
less stroke (NASCAR and PRO STOCK). Larger bores unshroud big valves and
large runner heads while short strokes reduce piston speed & rod angularity.
Rod angularity is what rocks the piston in the bore..hammering the skirts and
causing ring flutter which reduces sealing of combustion...hence they end up
using oil !!!! A quick veiw of ERL's website explains how the sleeves that they
put in aluminum blocks are longer to support the piston @ BDC when it's be-
ing driven into the skirts with 4",4.1",& 4.125" long arms. Now don't get me
wrong, I'm not bashing strokers as I've run quite a few over the years but to
me they're better suited for low RPM type street motors(trucks, heavy cars,
etc.)...unless you have the caliber of pocket book to maintain and freshen
often...which I never did. Fact is that 60% of an engine's rotating friction is
from the piston speed and ring tension. Shorter strokes make for less cubic
inches but will always be more efficient (horspower per in^3)..IIWM I'd go
for the LSX block @ 4.185"-4.200"bore range and a killer aftermarket (Lunati
or Callies) 3.62 crank for a 39x inch rev-happy horsepower beast.
But it does make a difference.
FormerVendor
Joined: Nov 2005
Posts: 191
Likes: 0
From: Indiana
If you're going to stay with a stock sleeve block you are limited. Depending on the core block the biggest you can really go is a 408 or 416 without running into immediate problems because of the short stock OEM sleeve length. It also depends on your true plans for this engine. We see it way too often where guys build their engine with the greatest intentions and advice from buddies but find themselves having to spend twice as much in the long run because they didn't build it right the first time or.... stay within the limits that the original build was intended for. Just my 2 cents.
